How can I apply blur shader, like you apply gray shader?

[pyroblinchik]

I'm new in shaders, and I don't understand how can I apply any shader to GLSurfaceView. Your project is only one I found, that realy works great, and I want blur shader in my camera app like you have gray, and I don't know how to apply it. Do you know how to do this? Is that possible? As I understand it, I need to change the files fragment_shader.glsl and vertex_shader.glsl. But how exactly? Thank you in advance. Your project is very informative